The present invention relates to an automobile headlamp that has a gauge for determining the amount of rightward or leftward displacement of the light beam axis of the headlamp. More particularly, the present invention pertains to an automobile headlamp having a displacement gauge that measures the amount of rightward or leftward rotational movements of an independently adjustable reflector, or that measures the amount of such movements of a headlamp that has an integrated unit of reflector and a lamp body.
An example of conventional headlamp of the same general type to which the invention pertains is described in Japanese Unexamined Publication No. Hei 3-155001. As shown in FIG. 6 of the present application, a displacement gauge c is mounted between an enclosing lamp body a, which is a headlamp component, and a reflector b, another headlamp component, that is supported rotatably along horizontal and vertical axes by an aiming mechanism. The design of the displacement gauge c includes a fixed holder 1, which is secured to the lamp body a, a movable holder 2, which is fitted into and travels forward and backward within the fixed holder 1, a slide pin 3, which rides within the movable holder 2 and is projected forward by a spring, and a zeroing adjustment screw 4, which extends through the end of the fixed holder 1 at the lamp body a and is threaded into the movable holder 2 from the rear. As the slide pin 3 is held flexibly in contact with the reflector b and slides within the movable holder 2 as the reflector b is rotated around the vertical axis, the relative positions of the scale lines 5 that are inscribed on the slide pin 3 and the movable holder 2 are changed. Thus, when zero adjustment is performed by rotating the zeroing adjustment screw 4, the amount of rightward or leftward displacement of the light beam axis L (the shifting of the light beam axis L), which is focused by the reflector b, can easily be determined by inspecting the relative scale lines 5 on the slide pin 3 and the movable holder 2.
In the conventional arrangement, to drive the zeroing adjustment screw 4, a screwdriver 6 engages a screwdriver engaging fitting 4a, which is mounted on the segment of the zeroing adjustment screw 4 that protrudes rearward beyond the lamp body a, as shown in FIG. 6. Since the zeroing adjustment screw 4 can be driven only from the rear of the lamp body a, the zeroing adjustment is difficult to carry out. Moreover, as little space is available, particularly at the rear of a headlamp that is mounted on an automobile, and inserting the screwdriver 6 is difficult, carrying out the zero adjustment is very complicated.